Production-ready mail server stack in a Docker container with SMTP, IMAP/POP3, LDAP auth, anti-spam/AV, DKIM/DMARC, and optional OAuth2 support.
18.8k stars2k forksMITlast commit Actively maintained
17 self-hosted Proton Mail alternatives
End-to-end encrypted hosted email service offering web and mobile clients, secure mailbox hosting, custom domain and alias support, and privacy-preserving account features with server-side controls to limit provider access to message content.
Alternatives to Proton Mail
All-in-one open-source mail and collaboration server with SMTP, IMAP, JMAP, CalDAV, CardDAV, and WebDAV, plus integrated anti-spam and phishing protection.
14.4k stars909 forkslast commit Actively maintained
Mailcow is a dockerized mail server suite providing SMTP/IMAP, webmail, anti-spam/anti-virus, and domain/mailbox administration via a unified web UI.
13.3k stars1.8k forksGPL-3.0last commit Actively maintained
#4
Mailu is a full-featured mail server distributed as Docker images, providing SMTP/IMAP/POP3, webmail, administration UI, and built-in security and anti-spam features.
7.5k stars997 forkslast commit Actively maintained
Open source webmail client for IMAP with address book, search, folders, and a customizable UI via plugins and skins.
7.1k stars1.8k forksGPL-3.0last commit Actively maintained
Go-based, modular mail server implementing SMTP/LMTP/IMAP with built-in DKIM/SPF/DMARC, storage backends (SQLite/Postgres/S3), Prometheus metrics and Docker support.
6.1k stars326 forksGPL-3.0last commit Actively maintained
#7
All-in-one secure mail server with SMTP, IMAP, webmail, automatic TLS (ACME), and built-in SPF/DKIM/DMARC plus junk filtering for low-maintenance domains.
5.8k stars218 forksMITlast commit Actively maintained
#8
A Bash script that auto-implements a full mail server (Postfix, Dovecot, DKIM, SpamAssassin) with TLS and PAM-based logins on Debian/Ubuntu.
2.2k stars341 forksGPL-3.0last commit Slowing down
#9
Open source groupware suite providing webmail, calendaring, address books, and shared resources via open standards like IMAP, CalDAV, and CardDAV.
2.2k stars320 forksGPL-2.0last commit Actively maintained
#10
WildDuck is a horizontally scalable IMAP/POP3 mail server that stores all mail in MongoDB, runs stateless Node.js workers, and provides a REST API for full server control.
2.1k stars278 forksEUPL-1.2last commit Actively maintained
#11
SnappyMail is a fast, modern webmail client (RainLoop fork) focused on performance, privacy, and secure IMAP access with optional PGP support and admin controls.
1.7k stars215 forksAGPL-3.0last commit Actively maintained
#12
High-performance, standards-compliant IMAP/POP3/LMTP server with flexible authentication, extensible plugin system (Lua, Sieve) and OpenSSL TLS support.
1.2k stars347 forkslast commit Actively maintained
Nextcloud Mail is a webmail app that connects to IMAP/SMTP accounts, offering a unified inbox and deep integration with other Nextcloud apps like Contacts and Calendar.
1k stars340 forksAGPL-3.0last commit Actively maintained
#14
Lightweight PHP webmail client for IMAP/SMTP servers, offering a simple interface, plugin extensibility, and broad compatibility with standard mail backends.
Activity unknown
Courier is an integrated mail server suite providing ESMTP (MTA), IMAP, POP3, webmail, and mailing lists with optional LDAP/MySQL/PostgreSQL-backed virtual accounts.
Activity unknown
Simple NixOS Mailserver provides NixOS modules to deploy a full email server with SMTP/IMAP, spam filtering, DKIM/DMARC/SPF, and TLS automation.
Activity unknown
Self-hosted enterprise collaboration suite providing email, webmail, calendaring, contacts, and administration for organizations.
Activity unknown
What replacing Proton Mail actually involves
Every option on this page is open source and free to run on your own hardware, so you own the data and there is no subscription to cancel. 12 of 17 shipped a commit in the last six months. Licences in this list: MIT, GPL-3.0, GPL-2.0, EUPL-1.2, AGPL-3.0. In exchange you take on hosting, backups and updates yourself.
Browse everything in Email Servers (SMTP/IMAP).
